Why is Friday 13th considered bad luck?
It's Friday 13th, the most cursed day in the calendar - allegedly - where everything is fated to go wrong. But where did we get the idea that it's a date when bad things happen?
On a walk through Birmingham city centre, everyone I ask has heard the notion that dark forces are at work on this "dreaded day". But do they believe it?
Sitting on a bench in Victoria Square are John and Gillie Hemmer who say they have "no qualms" about the date.
"My mum was actually born on Friday 13th," says Mrs Hemmer. "She always thought it was a lucky day - and so do I."
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Sitting nearby is Niall Johnstone, who thinks the whole idea is a joke.
"It was put there as something else to worry about," says the 26-year-old.
But in the shadow of the cathedral I find a woman who does believe in the perils of Friday 13th.
"It's just a feeling," says Aurora Marin, from Romania, as her sceptical companions cast their doubts.
The consensus on the street is that Ms Marin is in the minority.
Folklorist Anne Marie Lagram, from Shropshire, tells me she is a strong believer.
"I always feel a bit wary when I'm out and about and will send a message to my daughter to be doubly careful on that day," she says.
The origins of Friday 13th
Friday and the number 13 were unlucky in their own right, says Steve Roud, author of The Penguin Guide to the Superstitions of Britain and Ireland.
"Because Friday was the day of the crucifixion, Fridays were always regarded as a day of penance and abstinence.
"This religious belief spilled over into a general dislike of starting anything - or doing anything important - on a Friday."
Around the 1690s, an urban legend began circulating that it was unlucky to have 13 people around a table or in a group, he says.
Mrs Lagram says theories behind "unlucky 13" include the number of people present at the Last Supper or the number of witches to make a coven.
"The Victorians, who were intrigued by folklore, put Friday and 13 together and created a doubly unlucky day," says the author of the Country Wisdom and Folklore Diary.
Mr and Mrs Hemmer can reel off plenty more superstitions, from black cats to ladders and cracks in the pavement. But where do they all come from?
"Superstition comes from a time when life was uncertain and you felt you didn't have control," says Mr Roud.
"There became a notion of fate as being something you could control by doing lucky things or avoiding doing unlucky things."
Ms Marin and her friends Georgian Diaconu and Alina Gheorghita recount examples of these rituals.
"If something bad is going to happen you just knock on wood for the thing to not happen to you," says Mr Diaconu.
Ms Marin says she is scared of black cats: "If I see one I go back three steps."
Superstitions are learned from other people and persist because they are as good as any other strategy in situations beyond our control, says Michael Aitkin, psychology lecturer at Kings College London.
"Whatever action an individual is doing just before they experience something rewarding might become a superstitious behaviour, which is later repeated even if it is unrelated to the reward," he says.
These personal superstitions are common among people who have dangerous jobs or those that leave a lot to chance, says Mr Roud.
Indeed, some footballers are slaves to ridiculous rituals.
Mrs Hemming says once a lucky or unlucky notion gets into your head it is "very hard to un-know it" and more of an effort to avoid it than go along with it.
"If you know it's unlucky to walk on the cracks in the pavement and you've got an important interview that day you wouldn't take a chance on it," she says.
Many superstitions are to do with upsetting the order of the world, says Mr Roud.
"Opening umbrellas indoors is unlucky and a spade or a wild bird in the house means death," he says.
"It's the same with shoes on the table - they belong on the floor."
Some stay in our minds as they have become part of our language, says Mr Roud.
"Although I count myself as the least superstitious man in the country, I say 'fingers crossed' and 'touch wood'," he says.
Joan Carthy and Paulette Hall are sitting on a windowsill in Birmingham city centre waiting to go to work.
"The only one I won't do is walk under ladders," says Ms Carthy. "It's common sense, there's always something going to fall on you. And knowing my luck it'd be a house brick," she laughs.
"I've never had bad luck on Friday 13th," says Ms Hall. "It's just another day," Ms Carthy replies.
Optimistic Mr Johnstone says: "It's Friday - you've got to love a Friday."
This story was inspired by questions sent in by readers.